Suspension systems making use of elastomeric members or bushings between a generally fixed portion of the frame of the vehicle and an end of a shock absorber, strut, or other type of cylinder or suspension member are generally well known within the art.
Elastomeric bushings are generally used to reduce transmitted road noise and suspension vibration, and are also generally flexible enough to allow for articulation or movement during suspension travel. Typically, a suspension arm includes at least one elastomeric bushing pivotably attached to the vehicle frame.
In some car and light truck suspensions, tight clearances between the wheel or other components and suspension components require bushings that are offset or cantilevered from the suspension component. Typically, the geometric relationship of the cantilevered bushing to the suspension component induces high bending moments on the interface of the bushing and the suspension component during vehicle service. More specifically, service loads induce high bending moments, and subsequently high local stresses, in the portion of the suspension components connected to the bushing. Referring to FIG. 1, a force F of 33.2 kN to an offset bushing, as typically experienced in automotive or light truck applications, results in a stress of greater than 600 MPa being induced to the suspension component 10 at the point of connectivity 100 to the offset bushing. These high local stresses require that the suspension component 10 be constructed from high strength materials, i.e. forged steel, which precludes the use of lightweight materials, i.e. cast aluminum. By precluding the use of lightweight materials, the weight of heavier prior offset bushing designs disadvantageously limit the fuel economy and handling of the vehicle.
In light of the above, a need exists for an offset bushing design incorporated into lightweight suspension components, such as cast aluminum suspension components.